// Copyright 2018 gf Author(https://github.com/gogf/gf). All Rights Reserved.
//
// This Source Code Form is subject to the terms of the MIT License.
// If a copy of the MIT was not distributed with this file,
// You can obtain one at https://github.com/gogf/gf.

package gstr

// Levenshtein calculates Levenshtein distance between two strings.
// costIns: Defines the cost of insertion.
// costRep: Defines the cost of replacement.
// costDel: Defines the cost of deletion.
// See http://php.net/manual/en/function.levenshtein.php.
func Levenshtein(str1, str2 string, costIns, costRep, costDel int) int {
    var maxLen = 255
    l1 := len(str1)
    l2 := len(str2)
    if l1 == 0 {
        return l2 * costIns
    }
    if l2 == 0 {
        return l1 * costDel
    }
    if l1 > maxLen || l2 > maxLen {
        return -1
    }

    tmp := make([]int, l2+1)
    p1 := make([]int, l2+1)
    p2 := make([]int, l2+1)
    var c0, c1, c2 int
    var i1, i2 int
    for i2 := 0; i2 <= l2; i2++ {
        p1[i2] = i2 * costIns
    }
    for i1 = 0; i1 < l1; i1++ {
        p2[0] = p1[0] + costDel
        for i2 = 0; i2 < l2; i2++ {
            if str1[i1] == str2[i2] {
                c0 = p1[i2]
            } else {
                c0 = p1[i2] + costRep
            }
            c1 = p1[i2+1] + costDel
            if c1 < c0 {
                c0 = c1
            }
            c2 = p2[i2] + costIns
            if c2 < c0 {
                c0 = c2
            }
            p2[i2+1] = c0
        }
        tmp = p1
        p1 = p2
        p2 = tmp
    }
    c0 = p1[l2]

    return c0
}